use 5.20.0;
use List::AllUtils qw/ reduce min max /;

my @grid = (
    [ ],
   [ '', '', '', 1, '','' ],
   [ '', '',  2, 3, 4, '' ,'' ],
    [ '', 5, 6, 7, 8, 9, ],
[ '', '',  'A' ,'B', 'C' ],
[ '', '', '', 'D' ],
);

my %d = (
    U => [ -1, 0 ],
    R => [ 0, 1 ],
    L => [ 0, -1 ],
    D => [ 1, 0 ],
);

my $coord = [ 3,1 ];
while(<>) {
    chomp;
    $coord =  reduce { 
        my $n = $d{$b};
        use DDP;
        #   p $a;
        my $x = [
            map { $a->[$_] + $n->[$_] }
            0..1
        ];

        $grid[$x->[0]][$x->[1]] ? $x : $a;
    } $coord, split '';

    print $grid[$coord->[0]][$coord->[1]];

}